Researchers don't know what causes a pheochromocytoma. The tumor develops in specialized cells, called chromaffin cells, situated in the center of an adrenal gland. These cells release certain hormones, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine), that help control many body functions, such as heart rate, blood pressure and blood sugar.
The role of hormones
Adrenaline and noradrenaline are hormones that trigger your body's fight-or-flight response to a perceived threat. The hormones prompt higher blood pressure, a faster heart rate and a boost in other body systems that enable you to react quickly. A pheochromocytoma results in the irregular and excessive release of these hormones.
While most chromaffin cells reside in the adrenal glands, small clusters of these cells are also in the heart, head, neck, bladder, back wall of the abdomen and along the spine. Tumors in these chromaffin cells, called paragangliomas, may result in the same effects on the body.